We know decreasing animal product consumption decreases our IGF-1 levels, but how low do we have to go? How plant-based does our diet need to get? In my 2-min. video How Plant-Based to Lower IGF-1? the IGF-1 levels are compared between men and women eating conventional, vegetarian, and vegan diets.

Vegan men tended to have significantly higher testosterone levels than both vegetarians and meateaters (see graph here), which can be a risk factor for prostate cancer, the reason plant-based diets appear to reverse the progression of prostate cancer may be due to how low their IGF-1 drops (see Cancer Reversal Through Diet?).

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

69 responses to “Vegan Men: More Testosterone But Less Cancer”

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Nearly all of your posts and videos relate to the impact of whole plant foods on the physical body. Are you finding anything on the impact of diet on mental health, intelligence, personality and mental disease? This subject are really interests me. The closest thing I am aware of is your material on Alzhiemer’s. What about bipolar disorder? Schizophrenia? What about sleep, dreaming? Apnea is related to weight and hence is impacted by diet. What are you seeing in the literature?

The article says, “the reason plant-based diets appear to reverse the progression of prostate cancer may be due to how low their IGF-1 drops.” Notice first the “may,” then the fact that the linked video claiming “cancer reversal through diet” cites studies that all use comprehensive lifestyle interventions, not diet alone. Nothing here speaks directly to prostate cancer risk among vegans per se, nor definitively to IGF-1’s role in it.

The problem there—as is often the case in reporting on this topic—is that the author sees benefits from removal of poor-quality animal foods (including dairy and eggs, which are common inflammatory triggers/allergens), and then (fallaciously) concludes that all animal foods are bad. This kind of thinking puts one at risk of “throwing the baby out with the bathwater.”

Because there is plenty of nourishment to be gained from high-quality animal foods if you don’t think they cause prostate cancer and other health problems. Giving up ALL animal foods because SOME of them MIGHT be bad for you fits the above idiom exactly.

You stop gaining nourishment from animal foods if you stop eating them due to fear of prostate cancer or other problems. I could have said “animal source foods” to be clearer, but I suspect you know what I mean and are just being contrary.

So… that’s why animal eaters LIVE LONGER and have LESS CANCER than plant eaters?

I could go on about how one stops gaining “nourishment from sitting on ones behind” from not exercising or how eating a cup of blue berries everyday causes depression due to remembering the “good old days” with your friends who bit the dust/ lost their mind due to diet. I honestly believe that the meat is causing premature decline in cognitive performance as shown in your post.

I am a 33-year-old male, recently turned vegan (from vegetarianism). I suffer from low testosterone levels, and I have not seen them improve as a result of transitioning to veganism. (Stress and a one-time testosterone injection may have been a factor at some point in suppressing my own production of the hormone, but I am currently happy, low-stress and vegan and still have below norm levels.) Before I decide to take hormones for the rest of my life – I might not have a choice – I was wondering what vegan foods in particular could help me to boost my testosterone, so that I could try them over the next few months. I have also been avoiding soy recently due to the possibility that plant-based estrogens come into play.
I am quite struck that your website says that on average vegan men are doing better with testosterone.

I don’t know the answer to your specific question, but thought I would point out that Dr. Greger does have a video or an article about how licorice can lower testosterone levels. So, that would be one food/tea to definitely stay away from.

Thanks for your prompt responses. I didn’t realize that they came so fast.
I do eat plenty of fruit and vegetables, nuts, and whole grains. Should I be consuming more fat? Anything in particular? Any key nutrient that I might be missing?

I am not an expert in the area of raising testosterone. You can try including ground flaxseed in your diet to see if it helps. If your diet is made of whole unrefined plant foods then I am unsure what specifically there is I can recommend. Perhap others may respond to this issue.

Thanks for letting me know.
By the way, if there is any clarification needed, I am not sharing my story in order to discourage anyone from becoming vegan or anything. The internet is full of stuff about veganism not being good for one’s testosterone levels, but I have no idea if that’s credible at all. It might well be the case that I have a diagnosable condition that’s unrelated to my diet.
If anyone else on your team can chime in with more ideas, that would be greatly appreciated.
Thanks for your ideas!

She says “Cholesterol is a type of fat found only in animal foods. Vegans do not intake ANY dietary cholesterol. Human bodies do produce cholesterol, however, that’s only if the body is healthy. Cholesterol is produced in the liver. My liver had been abused by many years of drinking, smoking, caffeine, and then eventually, pregnancy.

Cholesterol is the precursor to all sex hormones (like estrogen, progesterone, etc). Without adequate cholesterol, the body cannot make hormones.”

Then she goes on to describe the dietary changes she made to improve her health “Eating as much saturated fat (coconut products, cacao butter) as possible because saturated fat stimulates cholesterol production. Also, eating plenty of other healthy fats, like olive oil, nuts, and avocados.” but adds ” I would be remiss if I didn’t mention that although I believe a low-fat vegan diet is excellent for reversing and curing many chronic diseases, that does NOT mean that it’s the right diet for everyone. A diet for healing is different than a diet for maintenance,”

Hi Mark, Don’t believe all research articles you read. Many of them are from biased resources and/or don’t actually take a full approach in determining all possible other casualities (where food was sourced for both groups, what other factors could be at play, etc). This site is frequently filled with scientific journals just like this that suffer from the same issues. The truth is, it’s very hard to maintain high testosterone levels on a vegan diet. Our stomaches are naturally better at processing meat (as we are carnivorous and only have 1 stomach) over vegetables due to the high phytic acid content. Furthermore, many essential vitamins and amino acids are hard to get in the right quantities without supplementing when on a vegan diet. A grassfed/freerange/wild caught/organic diet that is plant heavy is a much better approach to solving this problem for many individuals (including myself who previously had t levels that of an 80 year old man).
If you are doing a vegan diet for health reasons (and not for personal choice) I would suggest thinking of other solutions. Vegan diets are great for those who suffer from certain types of cancers while ketogenic diets are great for others. If you are not suffering from cancer or any other major illness which calls for a vegan diet, I would suggest starting with autoimmune Paleo and eventually converting to regular Paleo when you have any potential food intolerances that you should remove. Focus on fermented vegetables (pickles, kimchi, etc) to ensure the breakdown of phytic acid and high probiotic content. Eat 100% grassfed meat (preferably organ meat) for nutrient dencity, eat enough carbohydrates from things like sweet potatoes to manage stress hormones, healthy fats from wild caught fish, avocado, etc. Ensure you get 8-10 hours of sleep nightly, detox regularly via saunas, exercise regularly (3-4 days a week) but don’t over exercise, walk daily and spend plenty of time outside. Got a girl? Make sure you have sex a few times a week if possible. If you are missing any essential vitamins, ensure you are supplementing appropriately. Big vitamins to focus on is zinc, vitamin d, b complex, magnesium, fish oil. Don’t shotgun approach it though, check levels regularly if possible and slowly incorporate supplements in only if necessary. It’s best to get vitamins from natural food sources if at all possible. Try to keep your macros balanced (33% protein, 33% carbs, 33% fat) and adjust as needed for your body/energy levels. If you are over weight this will also play a part at which case you could go ketogenic until your at a good weight and then rebalance.

One study I read, mentioned vinegar is one step from being testosterone. I would drink it diluted, with and after meals daily. Remember, B 12 comes from animal products (eggs milk cheese), and without you have no stomach acid, which will negatively affect all systems, even causing bone spurs, and soft tissue calcium deposits. Without stomach acid, you will not produce enough niacin, which is needed to produce sex hormones. I suggest this supplement in doses of 50 mg. with each meal. Also, fermented, and sprouted soy presents a lowering of toxins, not an increase. Vegetarians have 50% less cancer causing toxins in their plasma. So, I suggest eating plant based diet, including fermented soy, and eggs milk and cheese and lots of pickles and vinegar products. Good health to you.

No not even the point that only animal products have b12 is completely true. There are microorganisms on the ground which animals eat so these microorganisms live in the gut from the animals. But the microorganisms are also present on vegetables from the ground etc which are covered with dirt but by washing and cleaning away all that dirt there is no b12 left nor isnt much b12 left in the animal products because there are not adequate portions of b12 in the meat. So just take a b12 supplement that is the best choice you can do. Even meat eaters have low b12 levels

Soy can be quite dangerous really. It DOES raise estrogen levels and high estrogen levels have been linked to blood clots, pulmonary embolism, and stroke. Speaking from personal experience, I began eating soy based protein bars as quick meals while I was working. After doing this for several months I developed a blood clot in my right calf and a month later I developed 2 more in my thigh.
My father in law went on a vegan diet that included soy and a few months later he developed a clot that went to his lungs and almost killed him.

Jo, try Biogenesis. When men take BioGenesis, they see a jump of about 5% in testosterone levels. BioGenesis has resveratrol which reduces aromatase- Aromatase is a female hormone that both men and women have. In women, Aromatase causes breast cancer, in men, Aromatase covers up testosterone. Check it out at cell-vitality.com

Jo, maybe it’s a little late to respond to you but i have encounter the same probleme as you.
The increase of fat (saturated, monosaturated) help a lot et give me the joyce of life again… I’ve restart a vegetarian diet (because of all the same claim i suppose you have found) and now try to do the same as 100% vegan, so coconut oil, avocado etc…

You say that vegan men have HIGHER testosterone… yet nowhere do you cite this. You link to an irrelevant graph (one also produced by you). Where is the research that shows vegan men have higher testosterone?

Here’s some more serious vegan muscle:
This guy recently broke a world record in weight lifting. “Congratulations to Strongman Patrik Baboumian who yesterday took a ten metre walk carrying more than half a tonne on his shoulders, more than anyone has ever done before. After smashing the world record the Strongman let out a roar of ‘Vegan Power’…” For more info:http://www.onegreenplanet.org/news/vegan-strongman-patrik-babaoumain-breaks-world-record/

Patrik did not build that body with a vegan diet. Getting jacked eating an omnivorous, meaty diet and then switching to veganism is not the same as building up from scratch. Bill Pearl who is also always brought up, falls into this category, though he was lacto-ovo, I believe.At least Patrik is big, badass, and strong though. Some of the guys you vegs like to cite are skinny (by musclehead/bodybuilding standards) and unimpressive. Absolutely not taking away from these guys, but the only problem I have with vegans is the widespread disingenuousness, and sometimes outright falsehoods.

These are not falsehoods at all…. High testosterone does not necessarily mean “big” or “beefy” or anything like that. It usually — note: usually — means more muscular (which does not necessarily mean bigger muscles), less fat around the breasts, less body percent fat, high energy, etc.

A former Mr. Universe is now vegan — granted, he was not vegan when he was Mr. Universe, HOWEVER, he still IS muscular, even in his 70s! Google “openly gay black vegan former mr universe” or something like that.

-1) I’m also in your shoes. As a male, I want to reduce my breast size. I have slightly done that, gradually, by fasting over 12 consecutive hours a day AND drinking a TON of water.
-2) I understand that these two lifestyle changes are easier said than done, and also, they take TIME — expect it to take at least 3- weeks before seeing any definite results.
-3) Another idea is to go on walks outside for just 25 minutes a day. 12 and a half minutes one day, and the same on the way back. You can even pace around your own apartment/house/dwelling 25 minutes a day.
-4) Finally, as noted, please stay away from processed foods — the fewer the ingredients, the better!

I have a couple of questions on the role of cholesterol and how it impacts testosterone:

1.) Does the human body produce its own cholesterol and if so, is there a need to supplement out bodies with more cholesterol through foods or do we manufacture enough?

2.) I’ve heard that to boost testosterone we do need high levels of cholesterol. Many people I’ve come across says the best source are eggs? How can vegan boost their testosterone via cholesterol without any animal products?

3.) I have learned that HDL are good fats, will HDL help boost testosterone?

Ron: Happily, your body makes all of the cholesterol that it needs. So, you don’t need to supplement. You really don’t want to supplement since adding more cholesterol is generally associated with higher risk of heart attacks.

I’m not sure how to answer you second two question except to point out this sentence from the post above: “Vegan men tended to have significantly higher testosterone levels than both vegetarians and meateaters…” So, being vegan looks to be a safe way to have higher testosterone levels naturally. You wouldn’t want more of any type of hormone than what is safe and correct for your body, would you???

Table 2 in the article shows that the total testosterone in vegans is 16% higher than meat eaters. However vegans have the lowest cholesterol and thus the highest SHBG, which blocks testosterone. The final result is that the free testosterone is only 5% higher for vegans than meat eaters, and that result is not ‘statistically significant’, i.e. it could be due to chance only. Even if it’s not due to chance, a difference of 5% in free testosterone will not have any observable effects.

I’ve been a vegan for 5 weeks, from meat eater. I can attest to the higher testosterone levels. My libido is way up. My strength has gone up. I feel more confident, more upbeat. I love working out now; mostly doing some pretty intense bike rides, and hitting the weights too. Whole foods veganism has completely changed my life. I had a quesadilla a little while back, felt like shit for the whole day and into the next.

Can you provide any evidence? Have you had your free/total testosterone and estradol levels actually checked before and after you made the diet change? If so, and its scientifically validated, whats your diet actually consist of?

Thanks for replying Jenna. I appreciate you taking the time to provide my data. From the sounds of it, there was no control in the study regarding what there diet specifically was. If the study also used younger individuals as the vegan test subjects, that means the study has to be completely thrown out as younger individuals are going to have a higher testosterone level anyways lol. Not quite sure why Dr Gregor would site this study though other than it agreeing with his life style choice. It would be nice if he could look at these studies with unbaised eyes. He needs to look openly at every study rather than just blindly pushing something bc it agrees with his current point of view.

Ex. Where the food is sourced from (is the meat grass fed, free range, organic)? How well the study was controlled? Who funded the study? Was there a repeat study? Were all subjects considered equal prior to the study?

Anyways, sorry for the rant. It just saddens me how much miss information is out there and how many internet doctors seem to be just posting material that agrees with their notion rather than pushing the envelope to look deeper. This is a scientific community problem.

Yes, vegan men (like me) have more testosterone than meat-eaters… BUT they also have higher sex hormone binding globulin… this means that the FREE testosterone in vegan men is no different from meat-eaters.

I remember seeing Dr. Greger quote a study claiming that those eating plant-based diets actually increased their testosterone levels as they aged. Is anyone familiar with the study he was quoting or remember which video it was? Thanks!

Truth hurts, you have no grounds to even challenge Dr. Greger on this. And he doesn’t rely on his on research, this is research and results created and ignored by the medical community and the public. Most of us here know better.

Would you mind providing the data. It makes no sense for INF-1 to decrease while Testosterone increases. Everything I’ve read and continue read illustrates that as Testosterone increases so does the production of INF-1. Plus, everyone I’ve ever known to go on a diet with plant protein (soy) ended up with testosterone in the toilet because soy is a phytoestrogen. What was the diet? How many people were in the study and how long was it for? Where did the study come out of?

ok… so… I’m convinced… at 45 I’m going low oil / whole food vegan, it’s been about a month and it’s been great… but I’m also on TRT (testosterone replacement therapy) and I am guessing that needs to stop… but… so many concerns.

Hey Robeii,
I suffered from testosterone deficiency (250 ng/dl at age 29) myself for awhile but was able to fix it through diet, exercise, stress management and proper sleep (700 ng/dl). I’m not a doctor, but I am computer scientist with a masters degree and so I am very scientific/unbaised in my approach to health. Destressing and proper sleep is essential to getting your testosterone right. 3-4 days a week, heavy lifting with compound exercises. Don’t over exercise though. From a dietary perspective, you really need to avoid anything that disrupts the endrocrine system including fluoride (water, toothpaste), pesticides, BPA/BPS, added hormones, GMOs, etc… basically you need to go back to basics with your diet and avoid added chemicals. I know this article claims vegan diets promote testosterone but my experience has been the complete opposite of this. What you first need to accept is that genetically we are all different and so some diets will work well for one and not for another. My diet prior to healing was moderately “healthy” by conventional standards before (low fat, low cholestrol, multigrains, not much red meat, etc) and it ruined my life. Changing my diet to a diet of all natural organic whole foods, high in healthy fats (olive oil, avocados, wild caught salmon, nuts), devoid of any grains (main source of carbs is veggies and sweet potatoes) and 100% grass fed, free-range chicken/red meat (perferably organ meat) turned my life around. I added supplements like ashwaganda initally to calm my adrenals down, magnesium to help with stressful times, probiotics to repopulate my gut flora and absolutely avoid phytoestrogens but thats pretty much it .

The biggest thing you have to realize is not every diet is made for everyone and there are many common foods like diary, grains, gluten, nuts, nightshades, etc that cause leaky gut, lead to internal inflammation and wreak havoc on your body. If you’re serious about getting your health in control, I suggest looking into trying a month or 2 on AIP (auto-immune paleo) to reset your gut health and then reintroduce foods to see what your reacting to. Good luck on your journey

Derrick, it looks like your diet is high in saturated fat which will increase cholesterol. That leads to boosting testosterone production and even slightly decreasing SHBG. The end result is that it will increase free testosterone, which is the only thing that matters. Was that the case?

That is true and there is a causality there. The biggest factor I noticed though was removing grains, gluten and limiting dairy. That and regular usage of sweat lodges (saunas) to get the built up garbage out of my system and make adequate time to laugh/destress. You can do everything right but if you aren’t laughing daily, destressing properly, getting the the old garbage out of your system and removing foods causing inflammation, the likelihood of improving testosterone is low.

1. Grapes – the skin of red grapes contains resveratrol which can raise testosterone levels and improve sperm epididymal motility (ability to swim)
2. Pomegranate – one of the best forms of antioxidants, iron, and vitamins A, C, and E, one glass of pomegranate juice a day can boost testosterone between 16 and 30 percent
3. Beans – black, kidney, and white beans are excellent sources of zinc and vitamin D
4. Extra Virgin Olive Oil – this heart-healthy fat increases testosterone levels 17 to 19 percent over three weeks
5. Coconut – another excellent source of fat that enables the body to produce the right kind of cholesterol for hormone production – coconut can also help reduce belly fat for weight loss which also helps increase testosterone levels
6. Cruciferous Vegetables – cauliflower, cabbage, and broccoli increase the excretion of estrogen that can reduce testosterone levels
7. Garlic – reduces the levels of cortisol when eaten raw for the best effects
8. Honey – the mineral boron in honey helps increase testosterone levels and nitric oxide in the body to open blood vessels and improve erectile strength

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